1. Field of the Invention
The invention relates to improvements in cleaning mechanisms for coating machines and the like. More particularly, the invention relates to a cleaning mechanism for mechanically cleaning the nozzle lips of the discharge opening of a fluid nozzle used primarily in the coating industry.
2. Description of the Prior Art
Gaseous fluid nozzles have been used in the coating industry for at least two basic functions, the first of which may be classified as "doctoring means," wherein the nozzle jet of fluid, usually gaseous fluid such as air, acts directly on a liquid or semi-liquid material which has been applied as a coating to the surface of a substrate, such as paper, film, foil, cloth or metal strip, in excess immediately ahead of or upstream from the particular nozzle in terms of movement of the substrate relative to the nozzle to reduce the coating to the desired thickness and smoothness.
Another basic use of gaseous fluid nozzles in the strip processing industry is as a "backing means", in which case, the air or other gaseous fluid jet is applied to one side of the moving strip, such as paper or plastic film, to maintain a uniform pressure against an object on the opposite side, such as a cooling roll or a rigid coating knife. One example of this "backing means" use is illustrated in U.S. Pat. No. 3,113,884.
It is not intended to limit the principles of the present invention to the paper coating industry or the coating of substrates of this general type, but rather it is fully contemplated that the principles of the present invention may be applied to nozzles for many uses, some of which may not be presently known.
It is extremely important in the coating industry that downtime and scrap be kept to a minimum. Since the coating station is usually only one part of a complicated expensive machine with a high rate of production, such as a paper board machine, or a steel galvanizing line, faults such as dirt in the nozzle produce scrap rapidly while stops disrupt many processes and restarting may take many minutes. Since a speck of dirt on or in the nozzle can cause a streak in a 200 inch wide strip running 1000 feet per minute or more, lost time and lost production cannot be tolerated.
These problems have long been recognized and U.S. Pat. Nos. 2,766,720 and 2,981,223 were offered to allow one nozzle subassembly to be quickly substituted for another. However, although these and variations thereon worked, it proved difficult, expensive and time consuming defeating the intended purpose.
Thus, the need has exited for an improved mechanism for efficiently cleaning coating control fluid nozzles in an extremely short period of time to reduce the amount of nozzle downtime. We know of no cleaning mechanism which accomplishes this result in a manner as efficient as our improved cleaning mechanism described in detail below.